Touch sensor integrated display device and method for driving the same

ABSTRACT

A touch sensor integrated display device and a method for driving the same are disclosed. The touch sensor integrated display device includes a display panel, each pixel of a pixel array including an OLED and a driving TFT applying a source-drain current to the OLED, the pixel array being divided into touch blocks, each touch block including pixels and a sensing target pixel line coupled to a subset of the pixels, and a panel drive circuit configured to, in a touch sensing period, supply a scan control signal and a sensing control signal to the sensing target pixel line corresponding to a touch block, set a gate-source voltage of the driving TFT coupled to the sensing target pixel line to turn on the driving TFT, and output a sensing value by sensing a change in the source-drain current of the driving TFT caused by a touch input.

This application claims the benefit of Korean Patent Application No.10-2015-0111866 filed on Aug. 7, 2015, which is incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND

Related Field

The present disclosure relates to a touch sensor integrated displaydevice and a method for driving the same.

Discussion of the Related Art

Touch sensors are being proposed which enable users to directly touch orget close to the screen and enter data with their finger or a pen whilewatching displays of a variety of home electronics or data communicationdevices. The touch sensors are used for various display devices becausethey are simple to use, have low possibility of malfunction, allow foruser input without using an additional input device, and enable theusers to operate them quickly and easily through content displayed onthe screen.

The touch sensors may be implemented by well-known technologies such ascapacitive sensing, infrared (IR) sensing, etc.

Capacitive sensing may be classified into add-on type, on-cell type, andin-cell type.

In the add-on type, as shown in FIG. 1, a display device 1 and 2 and atouch film 3 with touch sensors are separately manufactured, and thetouch film 3 is attached to the surface of the display device. In FIG.1, reference numeral 1 denotes a display panel, reference numeral 2denotes an encapsulation substrate, and reference numeral 4 denotes atouch IC. The add-on type has the problem of low visibility caused byits large thickness and the low brightness of the display device 1 and 2because a finished touch film 3 is mounted over the display device 1 and2.

In the on-cell type, touch sensors are directly formed on the surface ofan upper glass substrate of a display device. In case of the on-celltype, touch sensors are formed on the upper surface of a display device,with a reduction in thickness compared with the add-on type, but still adriving electrode layer and sensing electrode layer constituting thetouch sensors and an insulating film for insulating these layersincrease the entire thickness and the number of process steps, leadingto an increase in the manufacturing cost.

In the in-cell type, touch sensors are formed inside a display device,which is attracting a lot of attention in that the touch sensors can bemade thin. Known examples of the in-cell type touch sensors includemutual capacitance touch sensors and self-capacitance touch sensors. Inmutual capacitance sensing, driving electrode lines and sensingelectrode lines cross each other within a display panel to form touchsensors, a touch driving signal is applied to the driving electrodelines, and then touch input is sensed by detecting a change in mutualcapacitance at the touch sensors through the sensing electrode lines. Inself-capacitance sensing, touch electrodes and sensor lines are formedon a display panel, a touch driving signal is applied to the touchelectrode through the sensor lines, and touch input is sensed bydetecting a change in self-capacitance at the touch electrodes.

The in-cell type too requires signal lines (e.g., driving electrodelines, sensing electrode lines, and sensor lines) associated with touchto be added on the display panel. Moreover, the in-cell type requires anelectrode patterning process because an internal electrode used fordisplay is used as an electrode of the touch sensors to achieve a thinprofile and has large parasitic capacitance due to the coupling betweentouch sensors and pixels. This leads to a reduction in touch sensitivityand touch recognition accuracy.

In IR (infrared) sensing, as shown in FIG. 2, a display device 1 and 2and a touch bezel 5 with touch sensors are separately manufactured, andthe display device 1 and 2 and the touch bezel 5 are joined together. InFIG. 2, reference numeral 1 denotes a display panel, reference numeral 2denotes an encapsulation substrate, and reference numeral 4 denotes atouch IC. IR (infrared) sensing does not support multi-touch due to thelow response rate and the low touch resolution.

As seen from above, the conventional touch sensor technology requirescomplicated elements for touch sensing to be added on a display device,which complicates the manufacturing process, increases the manufacturingcost, and lowers touch sensing capabilities.

SUMMARY

An aspect of the present disclosure is to provide a touch sensorintegrated display device which can minimize additional elements fortouch sensing and enhance touch sensing capabilities.

In one aspect, there is a touch sensor integrated display devicecomprising a display panel including a pixel array, each pixel of thepixel array including an organic light emitting diode (OLED) and adriving thin film transistor (TFT) applying a source-drain current tothe OLED, the pixel array being divided into a plurality of touchblocks, each touch block including a plurality of pixels and a sensingtarget pixel line coupled to a subset of the plurality of pixels; apanel drive circuit configured to, in a touch sensing period, supply ascan control signal and a sensing control signal to the sensing targetpixel line corresponding to a touch block of the touch block of thetouch blocks, set a gate-source voltage of the driving TFT coupled tothe sensing target pixel line to turn on the driving TFT by applying atouch driving data voltage to a gate node of the driving TFT andapplying a reference voltage to a source node of the driving TFT, andoutput a sensing value by sensing, through a sensing line coupled to thedriving TFT, a change in the source-drain current of the driving TFTcaused by a touch input, the sensing line coupled to one or more pixelsin the touch block; and a timing controller configured to compare thesensing value with a predetermined reference value and detect the touchinput based on the comparison.

In one or more embodiments, the sensing line is coupled to another pixelin another touch block.

In one or more embodiments, the panel drive circuit is furtherconfigured to sense, through the sensing line, another change in thesource-drain current of the driving TFT during a compensation period todetermine characteristics of the driving TFT or the OLED coupled to thedriving TFT.

In one or more embodiments, the panel driving circuit is furtherconfigured to supply the scan control signal to the sensing target pixelline to program pixels coupled to the sensing target pixel lineaccording to image display data during an image display data addressperiod.

In one or more embodiments, each touch block further includesnon-sensing target pixel lines coupled to another subset of theplurality of pixels. The touch sensing periods of a number of the touchblocks may be assigned to a vertical active period for an image display.An image display data address periods, in which image display data iswritten on the non-sensing target pixel lines of each touch block, arefurther assigned to the vertical active period. The touch sensingperiods and the image display data address periods may be alternatelypositioned in the vertical active period. A transmission timing of asensing value of a first touch block of the touch blocks may overlap animage display data address period of a second touch block of the touchblocks adjacent to the first touch block.

In one or more embodiments, each touch block further includes horizontalpixel lines coupled to the plurality of pixels, each horizontal pixelline coupled to a corresponding subset of the plurality of pixels, asubset of the horizontal pixel lines including the sensing target pixelline. The touch sensing periods of a number of the touch blocks may beassigned to a vertical blank period between vertical active periods.Image display data may be written on the horizontal pixel lines of thetouch blocks in the vertical active periods. A transmission timing of asensing value with respect to a first touch block overlaps a touchsensing period of a second touch block adjacent to the first touchblock.

In one or more embodiments, the sensing target pixel line two or morepixel lines, the panel drive circuit simultaneously drives sensingtarget pixels, that are disposed vertically adjacent to one another andcoupled to the two or more pixel lines, and simultaneously samplessensing values of the sensing target pixels through the sensing linecoupled to the sensing target pixels.

In one or more embodiments, the sensing target pixel line includes twoor more pixel lines, the panel drive circuit sequentially drives sensingtarget pixels, that are disposed vertically adjacent to one another andcoupled to the two or more pixel lines, and simultaneously samplessensing values of the sensing target pixels through the sensing linecoupled to the sensing target pixels.

In one or more embodiments, an external compensation period, in which achange in electrical characteristics of the driving TFT is sensed, isassigned to a vertical blank period. In the external compensationperiod, the panel drive circuit may apply an external compensation datavoltage greater than the touch driving data voltage to the gate node ofthe driving TFT and applies the reference voltage to the source node ofthe driving TFT.

In one or more embodiments, an external compensation period, in which achange in electrical characteristics of the driving TFT is sensed, isassigned to a vertical blank period. The panel drive circuit may applythe scan control signal and the sensing control signal through thesensing target pixel line to couple the gate node and the source node ofthe driving TFT to corresponding signal lines during a sensing periodincluded in the external compensation period and to prevent the gatenode and the source node of the driving TFT from being electricallyfloated.

In one or more embodiments, the timing controller includes a memory anda memory controller configured to store image data input in the memoryat a first frame frequency and output data stored in the memory at asecond frame frequency less than the first frame frequency.

In one or more embodiments, a touch capacitor caused by the touch inputis connected to the gate node or the source node of the driving TFT andchanges the gate-source voltage of the driving TFT.

In another aspect, a method for driving a touch sensor integrateddisplay device, in which each pixel of a pixel array includes an organiclight emitting diode (OLED) and a driving thin film transistor (TFT)applying a source-drain current to the OLED is provided. The methodcomprises a first step of setting a touch sensing period with respect toa display panel, in which the pixel array is divided into a plurality oftouch blocks, each touch block including a plurality of pixels and asensing target pixel line coupled to a subset of the plurality ofpixels; a second step of, in the touch sensing period, supplying a scancontrol signal and a sensing control signal to the sensing target pixelline corresponding to a touch block of the touch blocks, setting agate-source voltage of the driving TFT coupled to the sensing targetpixel line to turn on the driving TFT by applying a touch driving datavoltage to a gate node of the driving TFT and applying a referencevoltage to a source node of the driving TFT, and outputting a sensingvalue by sensing, through a sensing line coupled to the driving TFT, achange in the source-drain current of the driving TFT caused by a touchinput, the sensing line coupled to one or more pixels in the touchblock; and a third step of comparing the sensing value with apredetermined reference value to detect the touch input based on thecomparison.

In one or more embodiments, a touch sensor integrated display devicecomprises a display panel including a pixel array, a plurality of pixelsin the pixel array coupled to a plurality of gate lines and a pluralityof sensing lines, each pixel of the pixel array including an organiclight emitting diode (OLED) and a driving transistor configured to applya current to the OLED, the pixel array being divided into a plurality oftouch blocks; and a panel drive circuit configured to: supply a firstscan control signal to gate lines of the plurality of gate lines coupledto pixels of the plurality of pixels in a touch block of the pluralityof touch blocks to program the pixels in the touch block according toimage display data during an image display data address period, supply asecond scan control signal to a subset of the gate lines coupled to asubset of the pixels in the touch block during a touch sensing period,and sense a change in a current through a driving transistor of a pixelin the touch block coupled to one of the subset of the gate lines and asensing line of the plurality of sensing lines to detect a touch inputduring the touch sensing period.

In one or more embodiments, the sensing line is coupled to another pixelin another touch block.

In one or more embodiments, the panel drive circuit is furtherconfigured to sense, through the sensing line, another change in thecurrent through the driving transistor during a compensation period todetermine characteristics of the driving transistor or an OLED of thepixel. The panel drive circuit may be further configured to apply afirst voltage between a gate node and a source node of the drivingtransistor during the compensation period and to apply a second voltageto the gate node and the source node of the driving transistor duringthe touch sensing period, the first voltage greater than the secondvoltage. The panel drive circuit may be further configured to couple agate node and a source node of the driving transistor to correspondingsignal lines during the compensation period to prevent the gate node andthe source node of the driving transistor from being electricallyfloated.

In one or more embodiments, the touch sensing period is included in avertical active period after the pixels in the touch block areprogrammed according to the image display data during the image displaydata address period. The touch sensing period may be included in thevertical active period before pixels of the plurality of pixels inanother touch block of the plurality of touch blocks are programmedaccording to the image display data during another image display dataaddress period.

In one or more embodiments, the touch sensing period is included in avertical blank period after the plurality of pixels in the plurality oftouch blocks are programmed according to the image display data duringthe image display data address period.

In one or more embodiments, the panel drive circuit is furtherconfigured to simultaneously supply the second scan control signal tothe subset of the gate lines during the touch sensing period.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a view showing a method for implementing touch sensors bycapacitive sensing according to the conventional art;

FIG. 2 is a view showing a method for implementing touch sensors by IR(Infrared) sensing according to the conventional art;

FIG. 3 is a view showing a touch sensor integrated display deviceaccording to one embodiment;

FIG. 4 is a view showing a configuration example of a pixel arraycomprising a plurality of pixels, which can be used as touch sensors,and a source drive IC;

FIG. 5 is a view showing a configuration of a pixel and a configurationexample of a sensing unit connected to a pixel according to oneembodiment;

FIG. 6 is a view showing a configuration of a pixel and a configurationexample of a sensing unit connected to a pixel according to anotherembodiment;

FIG. 7 shows a method of driving a touch sensor integrated displaydevice according to one embodiment;

FIG. 8 shows a first sensing approach for sensing a change in a gatesource voltage (Vgs) of a driving TFT caused by touch input when a touchcapacitor is connected to the gate node of the driving TFT;

FIG. 9 shows a circuit diagram of a capacitor network for performingtouch sensing according to the first sensing approach;

FIG. 10 shows a method of sensing a change in the Vgs of a driving TFTcaused by touch input, according to one embodiment of the first sensingapproach;

FIG. 11 shows a method of sensing a change in the Vgs of a driving TFTcaused by touch input, according to another embodiment of the firstsensing approach;

FIG. 12 shows a second sensing approach for sensing a change in the Vgsof a driving TFT caused by touch input when a touch capacitor isconnected to the gate node of the driving TFT;

FIG. 13 shows a circuit diagram of a capacitor network for performingtouch sensing according to the second approach;

FIG. 14 shows a method of sensing a change in the Vgs of a driving TFTcaused by touch input, according to one embodiment of the second sensingapproach;

FIG. 15 shows a method of sensing a change in the Vgs of a driving TFTcaused by touch input, according to another embodiment of the secondsensing approach;

FIG. 16 shows signal waveforms according to the driving method of FIG.10;

FIG. 17A shows an operation of a pixel during a reset period;

FIG. 17B shows an operation of a pixel during a sensing period;

FIG. 18 shows voltages at a gate and a source of a driving transistorfor sensing a touch according to the driving method of FIG. 10;

FIG. 19 shows current through the driving transistor for sensing a touchaccording to the driving method of FIG. 10;

FIG. 20 shows signal waveforms according to the driving method of FIG.11;

FIG. 21A shows how a pixel operates during a first reset period,according to the driving method of FIG. 11;

FIG. 21B shows how a pixel operates during a second reset period,according to the driving method of FIG. 11;

FIG. 21C shows how a pixel operates during a sensing period, accordingto the driving method of FIG. 11;

FIG. 22 shows voltages at a gate and a source of a driving transistorfor sensing a touch according to the driving method of FIG. 11;

FIG. 23 shows current through the driving transistor for sensing a touchaccording to the driving method of FIG. 11;

FIG. 24 shows signal waveforms according to the driving method of FIG.14;

FIG. 25A shows how a pixel operates during a first reset period,according to the driving method of FIG. 14;

FIG. 25B shows how a pixel operates during a second reset period,according to the driving method of FIG. 14;

FIG. 25C shows how a pixel operates during a sensing period, accordingto the driving method of FIG. 14;

FIG. 26 shows voltages at a gate and a source of a driving transistorfor sensing a touch according to the driving method of FIG. 14;

FIG. 27 shows current through the driving transistor for sensing a touchaccording to the driving method of FIG. 14;

FIG. 28 shows signal waveforms according to the driving method of FIG.15;

FIG. 29 shows an example of a cross-section structure of the driving TFTof a pixel;

FIG. 30 shows another example of a cross-section structure of thedriving TFT of a pixel;

FIG. 31 shows another example of a cross-section structure of thedriving TFT of a pixel;

FIGS. 32A through 32C show various examples of a method for converting adriving mode;

FIG. 33 illustrates configuration of a timing controller for changing aframe frequency;

FIG. 34 shows various examples of a change in a frame frequency;

FIG. 35 illustrates configuration of a touch sensing period;

FIG. 36 illustrates configuration, in which a pixel array of a displaypanel is divided into a plurality of blocks each including a sensingtarget pixel line;

FIG. 37 illustrates a method for assigning a touch sensing period to avertical active period;

FIG. 38 illustrates a method for assigning a touch sensing period to avertical blank period;

FIGS. 39 and 40 show an example of a gate signal applied to a sensingtarget pixel line and a non-sensing target pixel line adjacent to thesensing target pixel line in one block when a touch sensing period isassigned to a vertical active period as shown in FIG. 37;

FIG. 41 shows a transmission timing of a sensing value for reducing atouch sensing time when a touch sensing period is assigned to a verticalactive period as shown in FIG. 37;

FIGS. 42 and 43 show a driving timing of sensing target pixel lines in avertical blank period when a touch sensing period is assigned to thevertical blank period as shown in FIG. 38;

FIG. 44 shows a transmission timing of a sensing value for reducing atouch sensing time when a touch sensing period is assigned to a verticalblank period as shown in FIG. 38;

FIGS. 45 and 46 show an example of simultaneously sensing at least twoadjacent horizontal pixel lines of the same block and amplifying asensing value;

FIG. 47 shows an example of adding sensing deviations of adjacentsensing lines and amplifying a sensing value; and

FIGS. 48 and 49 illustrate methods for minimizing an influence of atouch input during external compensation in a touch driving mode.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Hereinafter, various embodiments of a touch sensor integrated displaydevice will be described with reference to FIGS. 3 to 49.

FIG. 3 is a view showing a touch sensor integrated display deviceaccording to one embodiment. FIG. 4 is a view showing a configurationexample of a pixel array comprising a plurality of pixels, which can beused as touch sensors, and a source drive IC. FIGS. 5 and 6 are viewsshowing the configuration of a pixel and a configuration example of asensing unit connected to the pixel according one embodiment.

The touch sensor integrated display device is implemented as an organiclight-emitting display device, especially, one comprising a pixel arrayfor external compensation. The touch sensor integrated display devicerequires no touch electrodes and sensor lines and can minimizeadditional elements for touch sensing because it senses touch inputusing an external compensation-type pixel array.

External compensation is a technique of sensing electricalcharacteristics of organic light-emitting diodes (hereinafter, OLEDs)and driving TFTs (thin film transistors) included in pixels andcorrecting input video data according to sensing values. An organiclight-emitting device comprising a pixel array for external compensationis disclosed in Republic of Korea Patent Application Nos.10-2013-0134256 (filed on Nov. 6, 2013), 10-2013-0141334 (filed on Nov.20, 2013), 10-2013-0149395 (filed on Dec. 3, 2013), 10-2014-0086901(filed on Jul. 10, 2014), 10-2014-0079255 (filed on Jun. 26, 2014),10-2014-0079587 (filed on Jun. 27, 2014), 10-2014-0119357 (filed on Sep.5, 2014), etc. which are incorporated herein by reference.

Referring to FIGS. 3 to 6, a touch sensor integrated display deviceaccording to an exemplary embodiment may comprise a display panel 10, atiming controller 11, a data drive circuit 12, and a gate drive circuit13. The data drive circuit 12 and the gate drive circuit 13 mayconstitute a panel drive circuit.

A plurality of data lines and sensing lines 14A and 14B and a pluralityof gate lines 15 intersect each other on the display panel 10, andpixels P capable of being compensated externally are arranged in amatrix form at the intersections to form a pixel array. The gate lines15 comprise a plurality of first gate lines 15A to which a scan controlsignal SCAN is supplied, and a plurality of second gate lines 15B towhich a sensing control signal SEN is supplied.

Each pixel P may be connected to one of the data lines 14A, one of thesensing lines 14B, one of the first gate lines 15A, and one of thesecond gate lines 15B. A plurality of pixels P included in a pixel unitUPXL may share one sensing line 14B. The pixel unit UPXL may comprise,but not be limited to, four pixels: a red pixel, a green pixel, a bluepixel, and a white pixel. Also, the pixels included in the pixel unitUPXL may be individually connected to a plurality of sensing lines,rather than sharing one sensing line. Each pixel P receives ahigh-potential driving voltage EVDD and a low-potential driving voltageEVSS from a power generator (not shown).

A pixel P for external compensation may comprise an OLED, a driving TFTDT, a storage capacitor Cst, a first switching TFT ST1, and a secondswitching TFT ST2. The TFTs may be implemented as p-type, or n-type, ora hybrid of p-type and n-type. Also, a semiconductor layer of the TFTsmay comprise amorphous silicon, polysilicon, or an oxide.

The OLED comprises an anode connected to a source node Ns, a cathodeconnected to an input terminal of low-potential driving voltage EVSS,and an organic compound layer located between the anode and the cathode.The organic compound layer may comprise a hole injection layer HIL, ahole transport layer HTL, an emission layer EML, an electron transportlayer ETL, and an electron injection layer EIL.

The driving TFT DL controls the amount of source-drain current(hereinafter, Ids) of the driving TFT DT flowing to the OLED accordingto a gate-source voltage (hereinafter, Vgs). The driving TFT DT has agate electrode connected to a gate node Ng, a drain electrode connectedto an input terminal of high-potential driving voltage EVDD, and asource electrode connected to a source node Ns. The storage capacitorCst is connected between the gate node Ng and the source node Ns tomaintain the Vgs of the driving TFT DT for a certain period of time. Thefirst switching TFT ST1 switches on an electrical connection between adata line 14A and the gate node Ng in response to a scan control signalSCAN. The first switching TFT ST1 has a gate electrode connected to afirst gate line 15A, a drain electrode connected to the data line 14A,and a source electrode connected to the gate node Ng. The secondswitching TFT ST2 switches on an electrical connection between thesource node Ns and a sensing line 14B in response to a sensing controlsignal SEN. The second switching TFT ST2 has a gate electrode connectedto a second gate line 15B, a drain electrode connected to the sensingline 14B, and a source electrode connected to the source node Ns.

A touch sensor integrated display device having such a pixel array forexternal compensation may operate in a first driving mode for displayingimages and making external compensation or in a second driving mode fordisplaying images, making external compensation, and performing touchsensing.

When the touch sensor integrated display device operates in the firstdriving mode, external compensation is made in a vertical blankinginterval during image display, or in a power-on sequence interval beforethe beginning of image display, or in a power-off sequence intervalafter the end of image display. The vertical blanking interval is thetime during which image data is not written (or not programmed), whichis arranged between vertical active periods in which one frame of imagedata is written (or programmed). The power-on sequence interval is thetime between the turn-on of driving power and the beginning of imagedisplay. The power-off sequence interval is the time between the end ofimage display and the turn-off of driving power.

When the touch sensor integrated display device operates in the seconddriving mode, touch sensing is performed in a horizontal blankinginterval during image display or in a vertical blanking interval duringimage display. The horizontal blanking interval is the time during whichno image data is written, which is arranged between horizontal activeperiods in which one horizontal line of image data is written. When thetouch sensor integrated display device operates in the second drivingmode, external compensation may be made in a vertical blanking interval,with touch sensing separately, or in the power-on sequence period, or inthe power-off sequence period.

The timing controller 11 may switch between the driving modes based oninformation about the user's mode selection, whether touch input ispresent or not, and the distance between the display device and theuser. The timing controller 11 may switch from the first driving mode tothe second driving mode or vice versa depending on information about theuser's mode selection via a remote control, a smartphone, buttons, andso on. Also, the timing controller 11 may determine whether touch inputis present or not, by performing as little touch sensing as possible,without affecting the picture quality, and may switch from the firstdriving mode to the second driving mode when touch input is sensed orswitch from the second driving mode to the first driving mode when notouch input is sensed for a certain period of time or longer. Also, thetiming controller 11 may determine the distance between the displaydevice and the user based on information input from a camera, infraredsensor, etc., and may switch from the first driving mode to the seconddriving mode if the user comes within a given distance or switch fromthe second driving mode to the first driving mode if the user moves thegiven distance away.

The timing controller 11 generates a data control signal DDC forcontrolling the operation timing of the data drive circuit 12 and a gatecontrol signal GDC for controlling the operation timing of the gatedrive circuit 13, based on timing signals such as a verticalsynchronization signal Vsync, a horizontal synchronization signal Hsync,a dot clock signal DCLK, and a data enable signal DE. In the firstdriving mode, the timing controller 11 may temporally separate an imagedisplay period and an external compensation period and generate thecontrol signals DDC and GDC differently for image display and externalcompensation, respectively. In the second driving mode, the timingcontroller 11 may temporally separate an image display period and anexternal compensation period and generate the control signals DDC andGDC differently for image display, external compensation, and touchsensing, respectively.

The timing controller 11 may adjust the frequencies of the gate controlsignal GDC and the data control signal DDC with respect to a framefrequency of k/i Hz so that digital video data received at a framefrequency of k Hz is written in the pixel array of the display panel 10at a frequency of k/i (k and i are positive integers), in order tosecure a sensing period for external compensation and/or a touch sensingperiod.

The gate control signal GDC comprises a gate start pulse GSP, a gateshift clock GSC, and a gate output enable signal GOE. The gate startpulse GSP is applied to a gate stage for generating a first scan signaland controls the gate stage to generate the first scan signal. The gateshift clock GSC is a clock signal that is commonly input into gatestages and shifts the gate start pulse GSP. The gate output enablesignal GOE is a masking signal that controls the output of the gatestages.

The data control signal DDC comprises a source start pulse SSP, a sourcesampling clock SSC, and a source output enable signal SOE. The sourcestart pulse SSP controls the timing of the start of data sampling of thedata drive circuit 12. The source sampling clock SSC is a clock signalthat controls the timing of data sampling in each source drive IC basedon a rising or falling edge. The source output enable signal SOEcontrols the output timing of the data drive circuit 12. The datacontrol signal DDC comprises a reference voltage control signal PRE andsampling control signal SAM for controlling the operation of a sensingunit 122 included in the data drive circuit 12. The reference voltagecontrol signal PRE controls the timing for applying a reference voltageto the sensing lines 14B. The sampling control signal SAM controls thetiming for sampling a sensing value resulting from external compensationor a sensing value resulting from touch sensing.

The timing controller 11 may store the sensing value resulting fromexternal compensation in a memory (not shown) and then compensatedigital video data RGB based on the sensing value to compensate fordifferences in the electrical characteristics of the driving TFTsbetween the pixels or differences in OLED degradation between thepixels. The timing controller 11 may compare the sensing value resultingfrom touch sensing with a predetermined reference value and obtain thecoordinates of the touch input position.

The timing controller 11, while operating for image display, maytransmit digital video data RGB input from an external video source tothe data drive circuit 12. The timing controller 11, while operating forexternal compensation, may transmit a certain level of digital data forexternal compensation to the data drive circuit 12. The timingcontroller 11, while operating for touch sensing, may transmit a certainlevel of digital data for touch sensing to the data drive circuit 12.

The data drive circuit 12 comprises at least one source drive IC(Integrated circuit) SDIC. The source drive IC SDIC may comprise a latcharray (not shown), a plurality of digital-to-analog converters(hereinafter, DACs) 121 connected to each data line 14A, a plurality ofsensing units 122 connected to the sensing lines 14B, a MUX 123 forselectively connecting the sensing units 122 to the analog-to-digitalconverter (hereinafter, ADC), and a shift register 124 for generating aselection control signal and sequentially turning on switches SS1 andSS2 in the MUX 123.

The latch array latches various kinds of digital data input from thetiming controller 11 and supplies it to the DAC based on the datacontrol signal DDC. For image display, the DAC may convert digital videodata RGB input from the timing controller 11 to a data voltage for imagedisplay and supply it to the data lines 14A. In an external compensationoperation, the DAC may convert digital data for external compensationinput from the timing controller 11 to a data voltage for externalcompensation and supply it to the data lines 14A. In a touch sensingoperation, the DAC may convert digital data for touch sensing input fromthe timing controller 11 to a data voltage for touch sensing and supplyit to the data lines 14A.

The sensing units 122 may supply a reference voltage Vref to the sensinglines 14B based on the data control signal DDC, or may sample a sensingvalue input through the sensing lines 14B and supply it to the ADC. Thissensing value may be one for external compensation or one for touchsensing.

The sensing units 122 may be implemented as voltage sensing-type shownin FIG. 5 or current sensing-type shown in FIG. 6.

The voltage sensing-type sensing unit 122 of FIG. 5 senses a voltagestored in a line capacitors LCa of a sensing line 14B according to theIds of a driving TFT DT, and may comprise a reference voltage controlswitch SW1, a sampling switch SW2, and a sample and hold portion S/H.The reference voltage control switch SW1 switches on an electricalconnection between an input terminal of reference voltage Vref and thesensing line 14B, in response to a reference voltage control signal PRE.The sampling switch SW2 switches on an electrical connection between thesensing line 14B and the sample and hold portion S/H in response to asampling control signal SAM. If the source node voltage of the drivingTFT DT changes according to the Ids of the driving TFT DT, the sampleand hold portion S/H samples and holds the source node voltage of thedriving TFT DT stored in the line capacitor LCa of the sensing line 14Bas a sensed voltage when the sampling switch SW2 is turned on, and thentransmits it to the ADC.

The current sensing-type sensing unit 122 of FIG. 6 directly senses theIds of the driving TFT transmitted through the sensing line 14B, and maycomprise a current integrator CI and a sample and hold portion SH. Thecurrent integrator CI integrates current data input through the sensingline 14B and generates a sensing value Vsen. The current integrator CIcomprises an amplifier AMP comprising an inverting input terminal (−)for receiving the Ids of the driving TFT from the sensing line 14B, anon-inverting input terminal (+) for receiving an amplifier referencevoltage Vpre, and an output terminal, an integrating capacitor Cfbconnected between the inverting input terminal (−) and output terminalof the amplifier AMP, and a reset switch RST connected to both ends ofthe integrating capacitor Cfb. The current integrator CI is connected tothe ADC through the sample and hold portion SH. The sample and holdportion SH may comprise a sampling switch SASS for sampling a sensingvalue Vsen output from the amplifier AMP and storing it in a samplingcapacitor Cs, and a holding switch HOLD for transmitting the sensingvalue Vsen stored in the sampling capacitor Cs to the ADC.

The gate drive circuit 13 generates a scan control signal SCAN for imagedisplay, external compensation, or touch sensing based on the gatecontrol signal GDC, and then supplies it to the first gate lines 15A.The gate drive circuit 13 generates a sensing control signal SEN forimage display, external compensation, or touch sensing based on the gatecontrol signal GDC, and then supplies it to the second gate lines 15B.

The principle of sensing touch input in the touch sensor integrateddisplay device will be briefly described. When a finger or conductiveobject (hereinafter, collectively referred to as a finger) touches thesurface of the display device, with the Vgs of the driving TFT set inadvance, the Vgs of the driving TFT changes due to a touch capacitorbetween the finger and the driving TFT. As the change in the Vgs of thedriving TFT leads to a change in the Ids of the driving TFT, a touch canbe detected based on the difference in the Ids of the driving TFTbetween pixels touched with the finger and the other pixels. The Ids isproportional to the square of a difference between Vgs and a thresholdvoltage of the driving TFT. Thus, the Ids is sensed as an amplifiedcurrent even if the amount of Vgs change caused by touch input is small,which offers an advantage to enhancing sensing capabilities.

Hereinafter, a concrete driving method for touch sensing under thesecond driving mode will be described in detail.

FIG. 7 shows a method of driving a touch sensor integrated displaydevice according to an exemplary embodiment.

Referring to FIG. 7, a reset period and a sensing period are set basedon a scan control signal and sensing control signal that are applied tothe gate lines 15A and 15B of the display panel 10 and a referencevoltage control signal PRE that controls an electrical connectionbetween the sensing lines 14B and the input terminal of referencevoltage Vref (S1).

In one embodiment, during the reset period, a Vgs required to turn onthe driving TFT DT is set by applying a data voltage for touch sensingto the gate node Ng of the driving TFT DT through the data line 14A anda reference voltage to the source node Ns of the driving TFT DT throughthe sensing line 14B (S1). Next, during the sensing period subsequent tothe reset period, a sensing value is output by sensing a change in theIds of the driving TFT DT caused by touch input (S2).

The sensing value is compared with a predetermined reference value todetect touch input (S3).

[First Sensing Approach for Sensing Change in Vgs of Driving TFT]

FIGS. 8 and 9 show a first sensing approach for sensing a change in theVgs of a driving TFT caused by touch input when a touch capacitor isconnected to the gate node of the driving TFT.

Referring to FIGS. 8 and 9, when a finger touches the surface of thedisplay device after the Vgs of the driving TFT DT is set in the storagecapacitor Cst in the reset period, a touch capacitor Ctouch between thefinger and the driving TFT DT is connected to the gate node Ng of thedriving TFT DT. The touch capacitor Ctouch connected to the gate node Ngis a finger capacitor between the gate electrode of the driving TFT DTand the finger. As the area contacted by the finger is larger than thearea occupied by one pixel, the touch capacitor Ctouch between thefinger and the driving TFT DT may be connected to the source node Ns ofthe driving TFT DT as well. The touch capacitor Ctouch connected to thesource node Ns is a finger capacitor between the source electrode of thedriving TFT DT and the finger. As the finger capacitor between thesource electrode of the driving TFT DT and the finger is smaller thanthe line capacitor LCa of the sensing line 14B, it has a very smalleffect on the change in the Vgs of the driving TFT. This is because, inthe first sensing approach, the touch capacitor Ctouch induces thechange in the Vgs of the driving TFT while the gate node Ng is floatingand the source node Ns is connected to the sensing line 14B.Accordingly, in the first sensing approach, it is deemed that there isno finger capacitor between the source electrode of the driving TFT DTand the finger.

When the touch capacitor Ctouch is connected to the gate node Ng whilethe gate node Ng is floating, the Vgs of the driving TFT DT changes andthe Ids of the driving TFT DT therefore changes. By changing thereference voltage applied to the source node Ns when the touch capacitorCtouch is connected to the gate node Ng while the gate node Ng isfloating, the Vgs of the driving TFT DT can be rapidly changed, and theIds of the driving TFT DT can be therefore rapidly changed.

FIGS. 10 and 11 show concrete driving methods for implementing the firstsensing approach of FIGS. 8 and 9.

Referring to FIG. 10, in one driving method for implementing the firstsensing approach, during the reset period, a Vgs required to turn on thedriving TFT DT is set by applying a data voltage for touch sensing tothe gate node Ng of the driving TFT DT through the data line 14A and areference voltage to the source node Ns of the driving TFT DT throughthe sensing line 14B (S11).

In one driving method, during the sensing period subsequent to the resetperiod, a sensing value Vsen is obtained by sensing the Ids of thedriving TFT DT resulting from change in the Vgs of the driving TFT DTwhile the gate node Ng is floating (S12). The Ids of the driving TFT DTat a touched area connected to the touch capacitor Ctouch is lower thanIds of a driving TFT DT at an untouched area, and this leads to adecrease in sensing value Vsen.

More concretely, an Ids flows through the driving TFT DT by the Vgs ofthe driving TFT DT, which is set in the reset period, and the potentialVs of the source node Ns rises by ΔVs due to the Ids. In this case, ifthe touch capacitor Ctouch is connected to the floating gate node Ng(that is, there is no touch input), the potential of the gate node Ngrises by ΔVs. Thus, there is no change in the Vgs of the driving TFT DT,and the static current mode is maintained. In contrast, if the touchcapacitor Ctouch is connected to the floating gate node Ng (that is,there is touch input), the potential of the gate node Ng rises by ΔVs′,which is smaller than ΔVs, due to voltage division between the storagecapacitor Cst and the touch capacitor Ctouch. Thus, the Vgs of thedriving TFT DT decreases compared to the initial one, and as a result,the Ids of the driving TFT DT also decreases.

$\begin{matrix}{{{Vgs}^{\prime} = {{Vgs} - \left( {{\Delta\;{Vs}} - {\Delta\;{Vs}^{\prime}}} \right)}}{{\Delta\;{Vs}^{\prime}} = {\Delta\;{Vs} \times \frac{CST}{\left( {{CST} + {CTOUCH}} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

That is, the gate-source voltage of the driving TFT DT for the touchedarea is the Vgs' of Equation 1. Accordingly, the Ids of the driving TFTDT for the touched area is lower than Ids of a driving TFT DT for theuntouched area according to the expression of TFT current(Ids=K(Vgs−Vth)²). By sensing this change in the Ids of the driving TFTDT, touch input can be detected. In Equation 1, CST denotes thecapacitance of the storage capacitor Cst, and CTOUCH denotes thecapacitance of the touch capacitor Ctouch.

In one driving method, touch input is detected by comparing the sensingvalue Vsen with a stored reference value (S13). As used herein, thereference value is determined based on the Vgs set during the resetperiod. If the difference between the sensing value Vsen of a pixel andthe reference value is smaller than or equal to a threshold, thecorresponding position associated with the pixel may be detected as theuntouched area, or if the difference between the sensing value Vsen of apixel and the reference value is greater than the threshold, thecorresponding position associated with the pixel may be detected as thetouched area.

FIG. 11 shows another driving method for implementing the first sensingapproach. The reset period is divided into a first reset period in whichthe gate node Ng of the driving TFT DT is connected to the data line14A, and a second reset period in which the gate node Ng of the drivingTFT DT is floating.

In another driving method, during the first reset period, a Vgs requiredto turn on the driving TFT DT is set by applying a data voltage fortouch sensing to the gate node Ng of the driving TFT DT through the dataline 14A and a reference voltage to the source node Ns of the drivingTFT DT through the sensing line 14B (S21).

In another driving method, during the second reset period subsequent tothe first reset period, a rapid change in the Vgs of the driving TFT DTis induced by varying (decreasing or increasing) the reference voltagewhile the gate node Ng of the driving TFT DT is floating (S22). Forexample, in another driving method, during the second reset period, thereference voltage applied to the source node Ns may decrease by ΔVswhile the gate node Ng of the driving TFT DT is floating. In this case,if the touch capacitor Ctouch is not connected to the floating gate nodeNg (that is, there is no touch input), the potential of the gate node Ngfalls by ΔVs. Thus, there is no change in the Vgs of the driving TFT DT,and the static current mode is maintained. In contrast, if the touchcapacitor Ctouch is connected to the floating gate node Ng (that is,there is touch input), the potential of the gate node Ng falls by ΔVs′,which is smaller than ΔVs, due to voltage division between the storagecapacitor Cst and the touch capacitor Ctouch. Thus, the Vgs of thedriving TFT DT increases compared to the initial one, and as a result,the Ids of the driving TFT DT also increases. By inducing a rapid changein the Vgs of the driving TFT DT, the time needed for sensing can bereduced.

In another driving method, during the sensing period subsequent to thesecond reset period, a sensing value Vsen is obtained by sensing the Idsof the driving TFT DT resulting from the change in the Vgs of thedriving TFT DT while the gate node Ng is floating (S23). The Ids of thedriving TFT DT at a touched area connected to the touch capacitor Ctouchis different from Ids of a driving TFT DT at an untouched area, and thisleads to a difference in sensing value Vsen. By sensing this change inthe Ids of the driving TFT DT, touch input can be detected.

In another driving method, touch input is detected by comparing thesensing value Vsen with a stored reference value (S24). As used herein,the reference value is determined based on the Vgs set during the firstreset period. If the difference between the sensing value Vsen of apixel and the reference value is smaller than or equal to a threshold,the corresponding position associated with the pixel may be detected asthe untouched area, or if the difference between the sensing value Vsenof a pixel and the reference value is greater than the threshold, thecorresponding position associated with the pixel may be detected as thetouched area.

[Second Sensing Approach for Sensing Change in Vgs of Driving TFT]

FIGS. 12 and 13 show a second sensing approach for sensing a change inthe Vgs of a driving TFT caused by touch input when a touch capacitor isconnected to the gate node of the driving TFT.

Referring to FIGS. 12 and 13, when a finger touches the surface of thedisplay device after the Vgs of the driving TFT DT is set in the storagecapacitor Cst in the reset period, a touch capacitor Ctouch between thefinger and the driving TFT DT is connected to the source node Ns of thedriving TFT DT. The touch capacitor Ctouch connected to the source nodeNs is a finger capacitor between the source node of the driving TFT DTand the finger. As the area contacted by the finger is larger than thearea occupied by one pixel, the touch capacitor Ctouch between thefinger and the driving TFT DT may be connected to the gate node Ng ofthe driving TFT DT as well. The touch capacitor Ctouch connected to thegate node Ng is a finger capacitor between the gate electrode of thedriving TFT DT and the finger. The finger capacitor between the gateelectrode of the driving TFT DT and the finger has no effect on thepotential of the gate node Ng. This is because, in the second sensingapproach, the touch capacitor Ctouch induces the change in the Vgs ofthe driving TFT while the potential of the gate node Ng is fixed and thesource node Ns is floating. Accordingly, in the second sensing approach,it is deemed that there is no finger capacitor between the gateelectrode of the driving TFT DT and the finger.

When the touch capacitor Ctouch is connected to the source node Ns whilethe source node Ns is floating, the Vgs of the driving TFT DT changes,thus the Ids of the driving TFT DT changes accordingly. By changing thedata voltage for touch sensing applied to the gate node Ng when thetouch capacitor Ctouch is connected to the source node Ns while thesource node Ns is floating, the Vgs of the driving TFT DT can be rapidlychanged, and the Ids of the driving TFT DT can be therefore rapidlychanged.

FIGS. 14 and 15 show concrete driving methods for implementing thesecond sensing approach for sensing a change in the Vgs of a driving TFTcaused by touch input.

Referring to FIG. 14, in one driving method for implementing the secondsensing approach, the reset period is divided into a first reset periodin which the source node Ns of the driving TFT DT is connected to theinput terminal of reference voltage, and a second reset period in whichthe source node Ns of the driving TFT DT is floating.

In one driving method, during the first reset period, a Vgs required toturn on the driving TFT DT is set by applying a data voltage for touchsensing to the gate node Ng of the driving TFT DT through the data line14A and a reference voltage to the source node Ns of the driving TFT DTthrough the sensing line 14B (S31).

In one driving method, during the second reset period subsequent to thefirst reset period, a rapid change in the Vgs of the driving TFT DT isinduced by causing the source node Ns of the driving TFT DT to float andoperating the driving TFT DT as a source follower type (S32).

In one driving method, during the sensing period subsequent to the resetperiod, a sensing value Vsen is obtained by sensing the Ids of thedriving TFT DT resulting from the change in the Vgs of the driving TFTDT while the gate node Ng is floating (S33). The Ids of the driving TFTDT at a touched area connected to the touch capacitor Ctouch is higherthan Ids of a driving TFT DT at an untouched area, and this leads to anincrease in sensing value Vs en.

More concretely, an Ids flows through the driving TFT DT by the Vgs ofthe driving TFT DT, which is set in the first reset period, thepotential Vs of the source node Ns rises in the second reset period dueto the Ids, and the potential Vg of the gate node Ng is fixed at thedata voltage for touch driving in the second reset period. In this case,the amount of increase in the potential Vs of the source node Ns differsdepending on whether the touch capacitor Ctouch is connected to thefloating source node Ns (that is, there is touch input) or not (that is,there is no touch input). Due to voltage division between a parasiticcapacitor Coled at two ends of the OLED and the touch capacitor Ctouch,the amount ΔVs of increase in the potential Vs of the source node Nsobserved when there is touch input is expressed by Equation 2:

$\begin{matrix}{{{Vgs}^{\prime} = {{Vgs} - {\Delta\;{Vs}}}}{{\Delta\;{Vs}} = \frac{{Ids} \times \Delta\; t}{\left( {{COLED} + {CTOUCH}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

On the contrary, the amount ΔVs of increase in the potential Vs of thesource node Ns observed when there is no touch input is not affected bythe touch capacitor Ctouch, and therefore the amount ΔVs without thetouch capacitor Ctouch becomes Ids*Δt/COLED, which is greater than thatobserved when there is touch input. That is, when the touch capacitorCtouch is connected to the floating source node Ns, the potential Vs ofthe source node Ns rises by a smaller amount than that observed when thetouch capacitor Ctouch is not connected to the floating source node Ns.Thus, the Vgs of the driving TFT DT increases relatively, and as aresult, the Ids of the driving TFT DT also increases. In Equation 2,COLED denotes the capacitance of the OLED capacitor Coled, and CTOUCHdenotes the capacitance of the touch capacitor Ctouch.

In one driving method, touch input is detected by comparing the sensingvalue Vsen with a stored reference value (S34). As used herein, thereference value is determined based on the Vgs set during the resetperiod. If the difference between the sensing value Vsen of a pixel andthe reference value is smaller than or equal to a threshold, thecorresponding position associated with the pixel may be detected as theuntouched area, or if the difference between the sensing value Vsen of apixel and the reference value is greater than the threshold, thecorresponding position associated with the pixel may be detected as thetouched area.

FIG. 15 shows another driving method for implementing the second sensingapproach. The reset period is divided into a first reset period in whichthe source node Ns of the driving TFT DT is connected to the inputterminal of reference voltage, and a second reset period in which thesource node Ns of the driving TFT DT is floating.

In another driving method, during the first reset period, a Vgs requiredto turn on the driving TFT DT is set by applying a data voltage fortouch sensing to the gate node Ng of the driving TFT DT through the dataline 14A and a reference voltage to the source node Ns of the drivingTFT DT through the sensing line 14B (S41).

In another driving method, during the second reset period subsequent tothe first reset period, a rapid change in the Vgs of the driving TFT DTis induced by causing the source node Ns of the driving TFT DT to float,operating the driving TFT DT as a source follower type, and varying(decreasing or increasing) the data voltage for touch sensing (S42). Forexample, in another driving method, during the second reset period, thedata voltage for touch sensing applied to the gate node Ng may decreaseby ΔVg while the source node Ns of the driving TFT DT is floating. Inthis case, if the touch capacitor Ctouch is not connected to thefloating source node Ns (that is, there is no touch input), thepotential of the source node Ns falls by ΔVg and gradually risesaccording to the source follower method. In contrast, if the touchcapacitor Ctouch is connected to the floating source node Ns (that is,there is touch input), the potential of the source node Ns falls byΔVg′, which is smaller than ΔVg, due to voltage division between theparasitic capacitor Coled at two ends of the OLED and the touchcapacitor Ctouch. Thus, the Vgs of the driving TFT DT decreasesaccording to the touch capacitor Ctouch, and as a result, the Ids of thedriving TFT DT also decreases accordingly. By inducing a rapid change inthe Vgs of the driving TFT DT, the time needed for sensing can bereduced.

In another driving method, during the sensing period subsequent to thesecond reset period, a sensing value Vsen is obtained by sensing the Idsof the driving TFT DT resulting from the change in the Vgs of thedriving TFT DT while the gate node Ng is floating (S43). The Ids of thedriving TFT DT at a touched area connected to the touch capacitor Ctouchis different from Ids of a driving TFT DT at an untouched area, and thisleads to a difference in sensing value Vsen. By sensing this change inthe Ids of the driving TFT DT, touch input can be detected.

In another driving method, touch input is detected by comparing thesensing value Vsen with a stored reference value (S44). As used herein,the reference value is determined based on the Vgs set during the firstreset period. If the difference between the sensing value Vsen of apixel and the reference value is smaller than or equal to a threshold,the corresponding position associated with the pixel may be detected asthe untouched area, or if the difference between the sensing value Vsenof a pixel and the reference value is greater than the threshold, thecorresponding position associated with the pixel may be detected as thetouched area.

[First Driving Example for Implementing First Sensing Approach]

FIG. 16 shows signal waveforms according to the driving method of FIG.10. FIGS. 17A and 17B show how a pixel operates during a reset periodand a sensing period. FIG. 18 shows voltages at a gate and a source of adriving transistor for sensing a touch according to the driving methodof FIG. 10. FIG. 19 shows current through the driving transistor forsensing a touch according to the driving method of FIG. 10.

Referring to FIG. 16, one driving method for implementing the firstsensing approach comprises a reset period {circle around (1)} for touchsensing and a sensing period {circle around (2)}, and may furthercomprise an image restoration period {circle around (3)}.

Referring to FIGS. 16 and 17A, during the reset period {circle around(1)}, the first switching TFT ST1 is turned on in response to a scancontrol signal SCAN of ON level, the second switching TFT ST2 is turnedon in response to a sensing control signal SEN of ON level, and thereference voltage control switch SW1 is turned on in response to areference voltage control signal PRE of ON level. During the resetperiod {circle around (1)}, a data voltage VT (e.g., 5 V) for touchsensing is applied to the gate node Ng of the driving TFT DT, and areference voltage Vref (e.g., 0 V) is applied to the source node Ns ofthe driving TFT DT. Thus, a Vgs required to turn on the driving TFT DT(which is higher than a threshold voltage Vth) is set.

Referring to FIGS. 16 and 17B, during the sensing period {circle around(2)}, the first switching TFT ST1 is turned off in response to a scancontrol signal SCAN of OFF level, the second switching TFT ST2 is turnedon in response to a sensing control signal SEN of ON level, and thereference voltage control switch SW1 is turned off in response to areference voltage control signal PRE of OFF level. During the sensingperiod {circle around (2)}, the gate node Ng of the driving TFT DT isdisconnected from the data line and floats, and the source node Ns ofthe driving TFT DT is disconnected from the input terminal of referencevoltage Vref and floats.

While the gate node Ng of the driving TFT DT and the source node Ns ofthe driving TFT DT are floating, the potential of the source node Ns ofthe driving TFT DT rises by ΔVs due to the Ids. In this case, if thetouch capacitor Ctouch is not connected to the floating gate node Ng(that is, there is no touch input), the potential of the gate node Ngrises by ΔVs. Thus, as shown in (A) of FIG. 18, there is no change inthe Vgs of the driving TFT DT, and the static current mode ismaintained. In contrast, if the touch capacitor Ctouch is connected tothe floating gate node Ng (that is, there is touch input), the potentialof the gate node Ng rises by ΔVs′, which is smaller than ΔVs, due tovoltage division between the storage capacitor Cst and the touchcapacitor Ctouch, and therefore, as shown in (B) of FIG. 18, the Vgs ofthe driving TFT DT decreases. Thus, as shown in FIG. 19, the Ids of thedriving TFT DT of the touched pixel is lower than Ids of a driving TFTDT of the untouched pixel. A sampling unit samples the Ids of thedriving TFT DT as a sensing value Vsen in response to a sampling signalSAM of ON level. In one aspect, the source node of the driving TFT DT ismaintained below a turn-on voltage (e.g., 9V) of the OLED during thereset period {circle around (1)} and the sensing period {circle around(2)}, such that the OLED does not emit light during the reset period{circle around (1)} and the sensing period {circle around (2)}.

The image restoration period {circle around (3)} is needed to maintainimage integrity before and after touch sensing. During the imagerestoration period {circle around (3)}, a data line and the gate node Ngof the driving TFT DT are electrically connected by the turn on of thefirst switching TFT ST1 in response to a scan control signal SCAN of ONlevel, a sensing line and the source node Ns of the driving TFT DT areelectrically connected by the turn on of the second switching TFT ST2 inresponse to a sensing control signal SEN of ON level, and the inputterminal of reference voltage Vref and the sensing line are electricallyconnected in response to a reference voltage control signal PRE of ONlevel. Accordingly, during the image restoration period {circle around(3)}, a data voltage VR for image restoration is applied to the gatenode Ng of the driving TFT DT, and a reference voltage Vref is appliedto the source node Ns of the driving TFT DT. The driving TFT DT allowsfor displaying the same image before and after touch sensing bysupplying an Ids, determined by the difference between the data voltageVR for image restoration and the reference voltage Vref, to the OLED andcausing the OLED to emit light.

[Second Driving Example for Implementing First Sensing Approach]

FIG. 20 shows signal waveforms according to the driving method of FIG.11. FIGS. 21A, 21B, and 21C show how a pixel operates during a firstreset period, a second reset period, and a sensing period. FIG. 22 showsvoltages at a gate and a source of a driving transistor for sensing atouch according to the driving method of FIG. 11. FIG. 23 shows currentthrough the driving transistor for sensing a touch according to thedriving method of FIG. 11.

Referring to FIG. 20, another driving method for implementing the firstsensing approach comprises a first reset period {circle around (1)} andsecond reset period {circle around (2)} for touch sensing and a sensingperiod {circle around (3)}, and may further comprise an imagerestoration period {circle around (4)}.

Referring to FIGS. 20 and 21A, during the first reset period {circlearound (1)}, the first switching TFT ST1 is turned on in response to ascan control signal SCAN of ON level, the second switching TFT ST2 isturned on in response to a sensing control signal SEN of ON level, andthe reference voltage control switch SW1 is turned on in response to areference voltage control signal PRE of ON level. During the first resetperiod {circle around (1)}, a data voltage VT (e.g., 7 V) for touchsensing is applied to the gate node Ng of the driving TFT DT, and areference voltage Vref (e.g., 6 V) of first level (LV1) is applied tothe source node Ns of the driving TFT DT. Thus, a Vgs required to turnon the driving TFT DT (which is higher than a threshold voltage Vth) isset.

Referring to FIGS. 20 and 21B, during the second reset period {circlearound (2)}, the first switching TFT ST1 is turned off in response to ascan control signal SCAN of OFF level, the second switching TFT ST2 isturned on in response to a sensing control signal SEN of ON level, andthe reference voltage control switch SW1 is turned on in response to areference voltage control signal PRE of ON level. During the secondreset period {circle around (2)}, the gate node Ng of the driving TFT DTis disconnected from the data line and floats, and a reference voltageVref (e.g., 0 V) of second level (LV2), which is lower than the firstlevel (LV1), is applied to the source node Ns of the driving TFT DT andtherefore the potential decreases by ΔVs (e.g., 6 V).

During the second reset period {circle around (2)}, if the touchcapacitor Ctouch is not connected to the floating gate node Ng (that is,there is no touch input), the potential of the gate node Ng falls by ΔVs(e.g., 6 V). Thus, there is no change in the Vgs of the driving TFT DT,and the static current mode is maintained. In contrast, if the touchcapacitor Ctouch is connected to the floating gate node Ng (that is,there is touch input), the potential of the gate node Ng falls by ΔVs′,which is smaller than ΔVs (e.g., 6 V), due to voltage division betweenthe storage capacitor Cst and the touch capacitor Ctouch. Thus, the Vgsof the driving TFT DT increases, and as a result, the Ids of the drivingTFT DT also increases. By inducing a rapid change in the Vgs of thedriving TFT DT, the time needed for sensing can be reduced.

Referring to FIGS. 20 and 21C, during the sensing period {circle around(3)}, the first switching TFT ST1 is turned off in response to a scancontrol signal SCAN of OFF level, the second switching TFT ST2 is turnedon in response to a sensing control signal SEN of ON level, and thereference voltage control switch SW1 is turned off in response to areference voltage control signal PRE of OFF level. During the sensingperiod {circle around (3)}, the gate node Ng of the driving TFT DT isdisconnected from the data line and floats, and the source node Ns ofthe driving TFT DT is disconnected from the input terminal of referencevoltage Vref and floats.

While the gate node Ng of the driving TFT DT and the source node Ns ofthe driving TFT DT are floating, the potential of the source node Ns ofthe driving TFT DT rises by ΔVs2 due to the Ids. In this case, if thetouch capacitor Ctouch is not connected to the floating gate node Ng(that is, there is no touch input), the potential of the gate node Ngrises by ΔVs2. Thus, as shown in (A) of FIG. 22, there is no change inthe Vgs of the driving TFT DT, and the static current mode ismaintained. In contrast, if the touch capacitor Ctouch is connected tothe floating gate node Ng (that is, there is touch input), the potentialof the gate node Ng rises by ΔVs2′, which is smaller than ΔVs2, due tovoltage division between the storage capacitor Cst and the touchcapacitor Ctouch, and therefore, as shown in (B) of FIG. 22, the Vgs ofthe driving TFT DT changes. The Vgs of a driving TFT DT to which touchinput is applied already has increased relatively in the second resetperiod {circle around (2)}, compared to the Vgs of a driving TFT DT towhich no touch input is applied. Thus, even if the Vgs of the drivingTFT DT to which touch input is applied changes to a lower level, it isstill higher than that of the driving TFT DT to which no touch input isapplied. Thus, as shown in FIG. 23 the Ids of the driving TFT DT of thetouched pixel is higher than Ids of a driving TFT DT of the untouchedpixel. A sampling unit samples the Ids of the driving TFT DT as asensing value Vsen in response to a sampling signal SAM of ON level. Inone aspect, the source node of the driving TFT DT is maintained below aturn-on voltage (e.g., 9V) of the OLED during the first reset period{circle around (1)}, the second reset period {circle around (2)}, andthe sensing period {circle around (3)}, such that the OLED does not emitlight during the first reset period {circle around (1)}, the secondreset period {circle around (2)}, and the sensing period {circle around(3)}.

The operational effects of the image restoration period {circle around(4)} are identical to those set forth above.

[First Driving Example for Implementing Second Sensing Approach]

FIG. 24 shows signal waveforms according to the driving method of FIG.14. FIGS. 25A, 25B, and 25C show how a pixel operates during a firstreset period, a second reset period, and a sensing period. FIG. 26 showsvoltages at a gate and a source of a driving transistor for sensing atouch according to the driving method of FIG. 14. FIG. 27 shows currentthrough the driving transistor for sensing a touch according to thedriving method of FIG. 14.

Referring to FIG. 24, one driving method for implementing the secondsensing approach comprises a first reset period {circle around (1)} andsecond reset period {circle around (2)} for touch sensing and a sensingperiod {circle around (3)}, and may further comprise an imagerestoration period {circle around (4)}.

Referring to FIGS. 24 and 25A, during the first reset period {circlearound (1)}, the first switching TFT ST1 is turned on in response to ascan control signal SCAN of ON level, the second switching TFT ST2 isturned on in response to a sensing control signal SEN of ON level, andthe reference voltage control switch SW1 is turned on in response to areference voltage control signal PRE of ON level. During the first resetperiod {circle around (1)}, a data voltage VT (e.g., 5 V) for touchsensing is applied to the gate node Ng of the driving TFT DT, and areference voltage Vref (e.g., 0 V) is applied to the source node Ns ofthe driving TFT DT. Thus, a Vgs required to turn on the driving TFT DT(which is higher than a threshold voltage Vth) is set.

Referring to FIGS. 24 and 25B, during the second reset period {circlearound (2)}, the first switching TFT ST1 is turned on in response to ascan control signal SCAN of ON level, the second switching TFT ST2 isturned off in response to a sensing control signal SEN of OFF level, andthe reference voltage control switch SW1 is turned on in response to areference voltage control signal PRE of ON level.

During the second reset period {circle around (2)}, the potential of thegate node Ng of the driving TFT DT is fixed at the data voltage VT(e.g., 5 V) for touch sensing, and the source node Ns of the driving TFTDT floats. During the second reset period {circle around (2)}, an Idsflows through the driving TFT DT by the Vgs of the driving TFT DT, whichis set in the first reset period, and the potential Vs of the sourcenode Ns rises by ΔVs' due to the Ids. That is, the driving TFT DToperates as a source follower type during the second reset period{circle around (2)}, thus inducing a change in the Vgs of the drivingTFT DT.

During the second reset period {circle around (2)}, the amount ofincrease in the potential Vs of the source node Ns differs depending onwhether the touch capacitor Ctouch is connected to the floating sourcenode Ns (that is, there is touch input) or not (that is, there is notouch input). Due to voltage division between a parasitic capacitorColed at two ends of the OLED and the touch capacitor Ctouch, the amountΔVs' of increase in the potential Vs of the source node Ns observed whenthere is touch input becomes Ids*Δt/(COLED+CTOUCH). On the contrary, theamount ΔVs' of increase in the potential Vs of the source node Nsobserved when there is no touch input is not affected by the touchcapacitor Ctouch, and therefore the amount ΔVs' without the touchcapacitor Ctouch becomes Ids*Δt/COLED, which is greater than thatobserved when there is touch input. That is, when the touch capacitorCtouch is connected to the floating source node Ns, the potential Vs ofthe source node Ns rises by a smaller amount than that observed when thetouch capacitor Ctouch is not connected to the floating source node Ns.Thus, the Vgs of the driving TFT DT increases according to the touchcapacitor Ctouch, and as a result, the Ids of the driving TFT DT alsoincreases.

Referring to FIGS. 24 and 25C, during the sensing period {circle around(3)}, the first switching TFT ST1 is turned off in response to a scancontrol signal SCAN of OFF level, the second switching TFT ST2 is turnedon in response to a sensing control signal SEN of ON level, and thereference voltage control switch SW1 is turned off in response to areference voltage control signal PRE of OFF level. During the sensingperiod {circle around (3)}, the gate node Ng of the driving TFT DT isdisconnected from the data line and floats, and the source node Ns ofthe driving TFT DT is disconnected from the input terminal of referencevoltage Vref and floats.

While the gate node Ng of the driving TFT DT and the source node Ns ofthe driving TFT DT are floating, the potential of the source node Ns ofthe driving TFT DT rises due to the Ids. If the touch capacitor Ctouchis not connected to the source node Ns (that is, there is no touchinput), the amount of increase in the potential of the source node Ns isequal to a first value, and the potential of the gate node Ng rises bythe first value. Therefore, the Vgs of the driving TFT DT is kept at asecond value, as shown in (A) of FIG. 26. In contrast, if the touchcapacitor Ctouch is connected to the source node Ns (that is, there istouch input), the amount of increase in the potential of the source nodeNs becomes ΔVs2, which is smaller than the first value, due to voltagedivision between the parasitic capacitor Coled at two ends of the OLEDand the touch capacitor Ctouch, the potential of the gate node Ng risesby ΔVs2, and therefore the Vgs of the driving TFT DT changes to a valuegreater than the second value, as shown in (B) of FIG. 26. In oneaspect, the source node of the driving TFT DT is maintained below aturn-on voltage (e.g., 9V) of the OLED during the first reset period{circle around (1)}, the second reset period {circle around (2)}, andthe sensing period {circle around (3)}, such that the OLED does not emitlight during the first reset period {circle around (1)}, the secondreset period {circle around (2)}, and the sensing period {circle around(3)}.

As shown in FIG. 27, the Ids of the driving TFT DT of the touched pixelis higher than Ids of a driving TFT DT of the untouched pixel. Asampling unit samples the Ids of the driving TFT DT as a sensing valueVsen in response to a sampling signal SAM of ON level.

The operational effects of the image restoration period {circle around(4)} are identical to those set forth above.

[Second Driving Example for Implementing Second Sensing Approach]

FIG. 28 shows signal waveforms according to the driving method of FIG.15.

Referring to FIG. 28, another driving method for implementing the secondsensing approach comprises a first reset period {circle around (1)} andsecond reset period {circle around (2)} for touch sensing and a sensingperiod {circle around (3)}, and may further comprise an imagerestoration period {circle around (4)}.

This driving method is different from the driving method of FIG. 24 inthat, during the second reset period {circle around (2)}, a rapid changein the Vgs of the driving TFT DT is induced by causing the source nodeNs of the driving TFT DT to float to operate the driving TFT DT as asource follower type and varying (decreasing or increasing) the datavoltage for touch sensing, and the other configuration elements aresubstantially identical to those explained with reference to FIG. 24.

Concretely, in this driving method, during the second reset period{circle around (2)}, the data voltage for touch sensing applied to thegate node Ng may decrease by ΔVg while the source node Ns of the drivingTFT DT is floating. In this case, if the touch capacitor Ctouch is notconnected to the floating source node Ns (that is, there is no touchinput), the potential of the source node Ns falls by ΔVg and graduallyrises according to the source follower method. In contrast, if the touchcapacitor Ctouch is connected to the floating source node Ns (that is,there is touch input), the potential of the source node Ns falls byΔVg′, which is smaller than ΔVg, due to voltage division between theparasitic capacitor Coled at two ends of the OLED and the touchcapacitor Ctouch. Thus, the Vgs of the driving TFT DT decreasesaccording to the touch capacitor Ctouch, and as a result, the Ids of thedriving TFT DT also decreases accordingly. By inducing a rapid change inthe Vgs of the driving TFT DT, the time needed for sensing can bereduced. In one aspect, the source node of the driving TFT DT ismaintained below a turn-on voltage (e.g., 9V) of the OLED during thefirst reset period {circle around (1)}, the second reset period {circlearound (2)}, and the sensing period {circle around (3)}, such that theOLED does not emit light during the first reset period {circle around(1)}, the second reset period {circle around (2)}, and the sensingperiod {circle around (3)}.

FIGS. 29 to 31 show various examples of a cross-section structure of thedriving TFT of a pixel.

In the above-described first sensing approach, the touch capacitorCtouch is connected between the gate node Ng of the driving TFT DT and afinger. Accordingly, the driving TFT DT needs to be configured in such amanner that the gate electrode GAT serves as an electrode of the touchcapacitor Ctouch, in order to implement the first sensing approach. Anexample of the structure of the driving TFT DT is as shown in FIGS. 29and 30, and the driving TFT DT may have any structure as long as thegate electrode GAT is exposed toward the light-emitting face through thesubstrate GLS.

In the above-described second sensing approach, the touch capacitorCtouch is connected between the source node Ns of the driving TFT DT anda finger. Accordingly, the driving TFT DT needs to be configured in sucha manner that the source electrode SD serves as an electrode of thetouch capacitor Ctouch, in order to implement the second sensingapproach. An example of the structure of the driving TFT DT is as shownin FIG. 31, and the driving TFT DT may have any structure as long as thesource electrode SD is exposed toward the light-emitting face throughthe substrate GLS. In FIG. 31, a metal light blocking pattern LSelectrically connected to the source electrode SD is exposed to thelight-emitting face through the substrate GLS.

In FIGS. 29 to 31, GLS denotes the substrate, LS denotes the metal lightblocking pattern, ACT denotes an active layer of the driving TFT, GAT,GAT1, GAT2 and GAT3 denote the gate electrode, SD denotes the sourceelectrode (or drain electrode) of the driving TFT, and GI, BUF, ILD,ESL, and PAS denote an insulating film.

[Driving Mode Conversion Method]

FIGS. 32A through 32C show various examples of a method for converting adriving mode.

If a touch sensor integrated display device performs a touch sensingoperation at all times, the touch sensor integrated display device maybe ineffective in terms of power consumption and image quality. In oneembodiment, the touch sensor integrated display device performs thetouch sensing operation only if necessary. Thus, the touch sensorintegrated display device according to the embodiment of the inventionmay be driven in a non-touch driving mode for the implementation of animage of high quality before information related to a touch is input,and may be driven in a touch driving mode when information related to atouch is input, thereby performing a touch sensing operation.

The timing controller 11 according to the embodiment of the inventionmay switch between the non-touch driving mode and the touch driving modebased on whether or not there is a touch input, user's mode selectioninformation, distance information between the display device and theuser, and the like.

More specifically, as shown in FIG. 32A, the timing controller 11determines whether or not there is a touch input through a minimum touchsensing operation not affecting the image quality. When a touch input issensed in the non-touch driving mode, the timing controller 11 maychange the non-touch driving mode to the touch driving mode. When atouch input is not sensed for a predetermined period of time in thetouch driving mode, the timing controller 11 may change the touchdriving mode to the non-touch driving mode. Further, the timingcontroller 11 may switch between the non-touch driving mode and thetouch driving mode depending on user's mode selection information inputthrough a remote controller shown in FIG. 32B, a smart phone, a button,etc. Further, the timing controller 11 determines a distance between thedisplay device and the user based on information input from a cameramounted on the display device or an infrared sensor CC shown in FIG.32C, etc. When the distance between the display device and the user iswithin a predetermined distance in the non-touch driving mode, thetiming controller 11 may change the non-touch driving mode to the touchdriving mode. When the distance between the display device and the useris beyond the predetermined distance in the touch driving mode, thetiming controller 11 may change the touch driving mode to the non-touchdriving mode.

[Method for Securing Sensing Time]

FIG. 33 illustrates configuration of a timing controller for changing aframe frequency, and FIG. 34 shows various examples of a change in aframe frequency.

In one or more embodiments, a sensing time is provided for an externalcompensation when the display device operates in the non-touch drivingmode. In addition, touch sensing time as well as the sensing time isprovided for the external compensation when the display device operatesin the touch driving mode. As shown in FIG. 33, the timing controller 11may include a memory DDR and a memory controller 11A in order to securethe sensing time. The memory controller 11A may control a writeoperation and a read operation of the memory DDR and store image datainput from the outside in the memory DDR at a first frame frequency (forexample, 120 Hz). Then, the timing controller 11 may output the imagedata stored in the memory DDR at a second frame frequency (for example,60 Hz) lower than the first frame frequency.

For example, the memory controller 11A may read input image data of 120Hz stored in the memory DDR at intervals of two frames and output it,thereby reducing an output frame frequency of data to 60 Hz as shown in(B) of FIG. 34. Further, the memory controller 11A may read input imagedata of 120 Hz stored in the memory DDR at intervals of four frames andoutput it, thereby reducing an output frame frequency of data to 30 Hzas shown in (C) of FIG. 34. Further, the memory controller 11A may readinput image data of 120 Hz stored in the memory DDR at intervals ofeight frames and output it, thereby reducing an output frame frequencyof data to 15 Hz as shown in (D) of FIG. 34. The lower the output framefrequency is, the longer a refresh period of one screen is. Thus, aportion of an increased hold period of the same image may be used as thesensing time. Hence, the embodiment of the invention can easily securethe sensing time by changing a frame frequency.

[Method for Securing Touch Sensing Time in Touch Driving Mode]

Various methods for securing a touch sensing time during a drive of thedisplay device in a touch driving mode are described with reference toFIGS. 35 to 44.

FIG. 35 illustrates configuration of a touch sensing period. FIG. 36illustrates configuration, in which a pixel array of a display panel isdivided into a plurality of blocks each including a sensing target pixelline. A sensing target pixel line herein refers to a pixel line (i.e., agate line 15A, a gate line 15B, or both) coupled to selected pixels froma group of pixels. The selected pixels may be disposed in a row.

Referring to FIG. 35, a touch sensing period TSEN includes a resetperiod, a sensing period, and an image restoration period. As describedabove, the embodiment of the invention sets a Vgs suitable to turn onthe driving TFT in the reset period, senses changes in an Ids of thedriving TFT in response to a touch input to obtain a sensing value inthe sensing period, and adjusts the Vgs of the driving TFT in the imagerestoration period in order to maintain image integrity before and aftertouch sensing, thereby preventing or reducing a horizontal pixel line onwhich the touch sensing has been performed, from being seen as a darkline. In the embodiment disclosed herein, the horizontal pixel line isdefined as a gate line coupled to a set of pixels positionedhorizontally adjacent to one another, and a plurality of sensing targetpixels are disposed horizontally adjacent to one another on the sensingtarget pixel line.

Because a contact area between the display panel and a finger (or aconductive object) touching the display panel is much greater than anarea occupied by one pixel, all of horizontal pixel lines do not need tobe used as the sensing target pixel line. Thus, as shown in FIG. 36, theembodiment of the invention divides the pixel array of the display panelinto a plurality of touch blocks BL1 to BLk and assigns at least onesensing target pixel line to each touch block, thereby reducing a touchresolution to less than a physical resolution of the display panel.Namely, the embodiment of the invention sets some (e.g., HLm, HL2 m, andHL3 m) of horizontal pixel lines HL1 to HL3 m included in each touchblock as sensing target pixel lines of each touch block.

FIG. 36 shows that a mth horizontal pixel line HLm is set as a sensingtarget pixel line of an ath touch block BLa, where ‘a’ is a positiveinteger, a 2mth horizontal pixel line HL2 m is set as a sensing targetpixel line of an (a+1)th touch block BLa+1, and a 3mth horizontal pixelline HL3 m is set as a sensing target pixel line of an (a+2)th touchblock BLa+2, as an example. A position and the number of sensing targetpixel lines included in each touch block may be changed. An example ofassigning a plurality of sensing target pixel lines to each touch blockand adding sensing values from a plurality of sensing target pixelsconnected to the same sensing line 14B in order to amplify a touchsensing value will be described later.

FIG. 37 illustrates a method for assigning a touch sensing period to avertical active period, and FIG. 38 illustrates a method for assigning atouch sensing period to a vertical blank period. A vertical activeperiod AP and a vertical blank period VBP are included in a singleframe.

The touch sensing may be performed on specific sensing target pixellines while writing image display data (or programming) pixels coupledto non-sensing target pixel lines. To this end, as shown in FIG. 37, aplurality of touch sensing periods TSEN(1) to TSEN(n), in which sensingtarget pixels are sensed, are arranged in a vertical active period AP,and one touch sensing period may be assigned to each touch block. Theplurality of touch sensing periods TSEN(1) to TSEN(n) and a plurality ofimage display data address periods TDRV(1) to TDRV(n) are alternatelyarranged in the vertical active period AP. The image display data iswritten (or programmed) on pixels coupled to the non-sensing targetpixel lines excluding the sensing target pixel lines from each touchblock through the image display data address period. For example, atouch input of a sensing target pixel line included in a first touchblock BL1 is sensed during a first touch sensing period TSEN(1), andimage display data is written (or programmed) on pixels coupled tonon-sensing target pixel lines included in the first touch block BL1during a first image display data address period TDRV(1). An externalcompensation period TRT may be additionally assigned to a vertical blankperiod VBP shown in FIG. 37. Changes in electrical characteristics (forexample, a threshold voltage, mobility, etc.) of the driving TFT (or theOLED) may be sensed in the external compensation period TRT for thepurpose of external compensation.

The touch sensing may be performed on sensing target pixel lines afterimage display data is written (or programmed) on pixels coupled to allof horizontal pixel lines of touch blocks. To this end, as shown in FIG.38, the image display data is written (or programmed) on pixels coupledto all of the horizontal pixel lines of the touch blocks including thesensing target pixel lines in a plurality of image display data addressperiods TDRV(1) to TDRV(n) assigned to a vertical active period AP.Further, a plurality of touch sensing periods TSEN(1) to TSEN(n), inwhich the sensing target pixels are sensed, are assigned to a verticalblank period VBP, and one touch sensing period may be assigned to eachtouch block. An external compensation period TRT may be additionallyassigned to the vertical blank period VBP shown in FIG. 38. Changes inelectrical characteristics (for example, a threshold voltage, mobility,etc.) of the driving TFT (or the OLED) may be sensed in the externalcompensation period TRT for the purpose of external compensation.

FIGS. 39 and 40 show an example of a gate signal applied to a sensingtarget pixel line and a non-sensing target pixel line adjacent to thesensing target pixel line included in one block when a touch sensingperiod is assigned to a vertical active period as shown in FIG. 37. FIG.41 shows a transmission timing of a sensing value for reducing a touchsensing time when a touch sensing period is assigned to a verticalactive period as shown in FIG. 37.

Referring to FIGS. 39 and 40 together with FIG. 36, a gate signal (forexample, a scan control signal SCAN and a sensing control signal SEN),which can cause the touch sensing to be performed in the vertical activeperiod AP, is applied to a mth horizontal pixel line HLm set as asensing target pixel line in an ath touch block BLa. The gate signal maybe selected among the gate signals shown in FIGS. 16, 20, 24, and 28,and the driving method for the touch sensing was described in thecorresponding figure.

The touch sensing time includes time required to transmit a sensingvalue, that is converted into a digital value by the ADC of the datadrive circuit 12, to the timing controller 11. In order to reduce thetouch sensing time, as shown in FIG. 41, the embodiment of the inventionmay overlap a transmission timing of the sensing value with the imagedisplay data address periods when the touch sensing period is assignedto the vertical active period AP as described above. For example, theembodiment of the invention may transmit a sensing value with respect toan ath touch block BLa during an image display data address periodTDRV(a+1) of an (a+1)th touch block BLa+1.

FIGS. 42 and 43 show a driving timing of sensing target pixel lines in avertical blank period when a touch sensing period is assigned to thevertical blank period as shown in FIG. 38. FIG. 44 shows a transmissiontiming of a sensing value for reducing a touch sensing time when a touchsensing period is assigned to a vertical blank period as shown in FIG.38.

Referring to FIGS. 42 and 43 together with FIG. 36, a gate signal (forexample, a scan control signal SCAN and a sensing control signal SEN) isapplied, so that sensing target pixel lines HLm, HL2 m, HL3 m, and HL4 mof touch blocks BLa to BLa+3 are sequentially sensed during a verticalblank period VBP. The gate signal may be selected among the gate signalsshown in FIGS. 16, 20, 24, and 28, and the driving method for the touchsensing was described in the corresponding figure.

In order to reduce the touch sensing time, as shown in FIG. 44, theembodiment of the invention may overlap a transmission timing of thesensing value of a touch block with a touch sensing period of asubsequent touch block. For example, the embodiment of the invention maytransmit a sensing value with respect to an (a)th touch block BLa duringa touch sensing period TSEN (a+1) of an (a+1)th touch block BLa+1.

[Method for Improving Touch Sensing Performance in Touch Driving Mode]

FIGS. 45 and 46 show an example of simultaneously sensing at least twoadjacent horizontal pixel lines of the same block and amplifying asensing value. FIG. 47 shows an example of adding sensing deviations ofadjacent sensing lines and amplifying a sensing value.

Referring to FIG. 45, the embodiment of the invention may set aplurality of sensing target pixel lines HLm-3, HLm-2, HLm-1, and HLm inone touch block BLa, simultaneously apply a gate signal to sensingtarget pixels P, that are disposed vertically adjacent to one another onthe sensing target pixel lines HLm-3, HLm-2, HLm-1, and HLm, andsimultaneously sample sensing values of the sensing target pixels Pthrough the same sensing line 14B, thereby amplifying a sensing value ofthe one touch block BLa. The amplified sensing value is applied to theADC through the same sensing line 14B. If the sensing value is verysmall, it is difficult to distinguish the sensing value from a noise.Thus, it is impossible to determine whether or not there is a touchinput. The embodiment of the invention increases the sensing valuethrough the above-described simultaneously sensing method and canimprove a touch sensing performance. Further, the embodiment of theinvention can increase a sensing speed by simultaneously applying thegate signal as described above.

Referring to FIG. 46, the embodiment of the invention may set aplurality of sensing target pixel lines HLm-3, HLm-2, HLm-1, and HLm inone touch block BLa, sequentially apply a gate signal to sensing targetpixels P, that are disposed vertically adjacent to one another on thesensing target pixel lines HLm-3, HLm-2, HLm-1, and HLm, andsimultaneously sample sensing values of the sensing target pixels Pthrough the same sensing line 14B, thereby amplifying a sensing value ofthe one touch block BLa and preventing or reducing a screen block frombeing seen during the touch sensing.

As another method for amplifying the sensing value, as shown in FIG. 47,the embodiment of the invention may obtain a sensing deviation valueASEN corresponding to a difference between a sensing value of eachsensing line and a reference value through the timing controller, addseveral horizontally adjacent sensing deviation values ASEN whileshifting each sensing deviation value ASEN, and calculate a totalsensing deviation value SUM. Because the total sensing deviation valueSUM is greater than the sensing deviation value ASEN, it is easy todetermine whether or not there is a touch input.

[Method for Minimizing Touch Influence During External Compensation inTouch Driving Mode]

FIGS. 48 and 49 illustrate methods for minimizing a touch influenceduring external compensation in a touch driving mode.

As described above, an external compensation operation for compensatingfor changes in electrical characteristics of the driving TFT isperformed to go side by side with a touch sensing operation even in thetouch driving mode, in which the touch sensing is performed. Theexternal compensation operation may be performed in the externalcompensation period TRT of the vertical blank period VBP. When theelectrical characteristics (for example, a threshold voltage, mobility,etc.) of the driving TFT are sensed using the external compensationperiod TRT, a sensing value of the external compensation may be affectedby the touch input and distorted. Because the sensing value of theexternal compensation is a result of sensing a source node voltage ofthe driving TFT DT, the source node voltage of the driving TFT DT may bedistorted during the external compensation sensing if the Vgs and theIds of the driving TFT DT change due to the touch input.

As a method for minimizing a distortion of the sensing value of theexternal compensation caused by the touch input, the embodiment of theinvention may apply an external compensation data voltage greater than atouch driving data voltage to a gate node of the driving TFT in theexternal compensation period TRT and apply a reference voltage to asource node of the driving TFT in the external compensation period TRT,thereby increasing the Vgs of the driving TFT to a value greater thanthe Vgs of the driving TFT determined during the touch sensing. When theVgs of the driving TFT increases, the Ids of the driving TFT mayincrease in proportion to an increase in the Vgs. Therefore, a sensingspeed increases, and thus the distortion of the sensing value can beminimized. FIG. 48 shows a driving waveform thereof. The externalcompensation is performed during a reset period Ti, in which the Vgs ofthe driving TFT is set to a large value, and a sensing period Ts, inwhich the source node voltage of the driving TFT is sensed at a maximumsensing speed. In the external compensation, changes in the electricalcharacteristics of the driving TFT are determined based on a magnitudeof the sensing value.

As another method for minimizing the distortion of the sensing value ofthe external compensation caused by the touch input, the embodiment ofthe invention may apply a scan control signal SCAN and a sensing controlsignal SEN at an on-level through sensing target pixel lines to couplethe gate node and the source node to corresponding signal lines (e.g.,data line 14A and sensing line 14B) during a sensing period Ts, therebypreventing one of the gate node and the source node of the driving TFTfrom being electrically floated in the sensing period Ts. As describedabove, when only one of the gate node and the source node of the drivingTFT is floated in the reset period Ti, the Vgs of the driving TFTchanges due to the touch input. When the gate node and the source nodeof the driving TFT are simultaneously connected to each signal line (forexample, the data line 14A and the sensing line 14B) during the sensingperiod Ts, the Vgs of the driving TFT does not change even if there is atouch input. In this instance, the Ids of the driving TFT depends onlyon the electrical characteristics of the driving TFT. FIG. 49 shows adriving waveform thereof. The external compensation according to theembodiment of the invention simultaneously applies the scan controlsignal SCAN and the sensing control signal SEN at an on-level during thesensing period Ts, thereby preventing the touch input from affecting theVgs of the driving TFT. In the external compensation, changes in theelectrical characteristics of the driving TFT are determined based on amagnitude of the sensing value with respect to the source node voltageof the driving TFT.

As described above, the touch sensor integrated display device accordingto the embodiment of the invention requires no touch electrodes andsensor lines. Thus, various embodiments of the touch sensor integrateddisplay device disclosed herein can minimize additional elements fortouch sensing because it senses touch input using an externalcompensation-type pixel array.

Moreover, the touch sensor integrated display device according to theembodiment of the invention senses a change in the Ids of the drivingTFT resulting from a change in the Vgs of the driving TFT caused bytouch input. Thus, the Ids is sensed as an amplified current even if theamount of Vgs change caused by touch input is small, and this offers anadvantage to enhancing sensing capabilities.

Moreover, the touch sensor integrated display device according to theembodiment of the invention can improve the touch sensing performance inthe touch driving mode and also minimize an influence of touch inputduring the external compensation in the touch driving mode, therebyincreasing the accuracy of the touch sensing.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A touch sensor integrated display devicecomprising: a display panel including a pixel array, each pixel of thepixel array including an organic light emitting diode (OLED) and adriving thin film transistor (TFT) applying a source-drain current tothe OLED, the pixel array being divided into a plurality of touchblocks, each touch block including a plurality of pixels and a sensingtarget pixel line coupled to a subset of the plurality of pixels; apanel drive circuit configured to, in a touch sensing period, supply ascan control signal and a sensing control signal to the sensing targetpixel line corresponding to a touch block of the touch blocks, set agate-source voltage of the driving TFT coupled to the sensing targetpixel line to turn on the driving TFT by applying a touch driving datavoltage to a gate node of the driving TFT and applying a referencevoltage to a source node of the driving TFT, and output a sensing valueby sensing, through a sensing line coupled to the driving TFT, a changein the source-drain current of the driving TFT caused by a touch input,the sensing line coupled to one or more pixels in the touch block; and atiming controller configured to compare the sensing value with apredetermined reference value and detect the touch input based on thecomparison, wherein the sensing line is coupled to another pixel inanother touch block.
 2. The touch sensor integrated display device ofclaim 1, wherein the panel drive circuit is further configured to sense,through the sensing line, another change in the source-drain current ofthe driving TFT during a compensation period to determinecharacteristics of the driving TFT or the OLED coupled to the drivingTFT.
 3. The touch sensor integrated display device of claim 1, whereinthe panel driving circuit is further configured to supply the scancontrol signal to the sensing target pixel line to program pixelscoupled to the sensing target pixel line according to image display dataduring an image display data address period.
 4. The touch sensorintegrated display device of claim 1, wherein each touch block furtherincludes non-sensing target pixel lines coupled to another subset of theplurality of pixels, wherein touch sensing periods of a number of thetouch blocks are assigned to a vertical active period for an imagedisplay, wherein image display data address periods, in which imagedisplay data is written on the non-sensing target pixel lines of eachtouch block, are further assigned to the vertical active period, andwherein the touch sensing periods and the image display data addressperiods are alternately positioned in the vertical active period.
 5. Thetouch sensor integrated display device of claim 4, wherein atransmission timing of a sensing value of a first touch block of thetouch blocks overlaps an image display data address period of a secondtouch block of the touch blocks adjacent to the first touch block. 6.The touch sensor integrated display device of claim 4, wherein anexternal compensation period, in which a change in electricalcharacteristics of the driving TFT is sensed, is assigned to a verticalblank period, and wherein in the external compensation period, the paneldrive circuit applies an external compensation data voltage greater thanthe touch driving data voltage to the gate node of the driving TFT andapplies the reference voltage to the source node of the driving TFT. 7.The touch sensor integrated display device of claim 4, wherein anexternal compensation period, in which a change in electricalcharacteristics of the driving TFT is sensed, is assigned to a verticalblank period, and wherein the panel drive circuit applies the scancontrol signal and the sensing control signal through the sensing targetpixel line to couple the gate node and the source node of the drivingTFT to corresponding signal lines during a sensing period included inthe external compensation period and to prevent the gate node and thesource node of the driving TFT from being electrically floated.
 8. Thetouch sensor integrated display device of claim 1, wherein each touchblock further includes horizontal pixel lines coupled to the pluralityof pixels, each horizontal pixel line coupled to a corresponding subsetof the plurality of pixels, a subset of the horizontal pixel linesincluding the sensing target pixel line, wherein touch sensing periodsof a number of the touch blocks are assigned to a vertical blank periodbetween vertical active periods, and wherein image display data iswritten on the horizontal pixel lines of the touch blocks in thevertical active periods.
 9. The touch sensor integrated display deviceof claim 8, wherein a transmission timing of a sensing value of a firsttouch block of the touch blocks overlaps a touch sensing period of asecond touch block of the touch blocks adjacent to the first touchblock.
 10. The touch sensor integrated display device of claim 8,wherein an external compensation period, in which a change in electricalcharacteristics of the driving TFT is sensed, is further assigned to thevertical blank period, and wherein in the external compensation period,the panel drive circuit applies an external compensation data voltagegreater than the touch driving data voltage to the gate node of thedriving TFT and applies the reference voltage to the source node of thedriving TFT.
 11. The touch sensor integrated display device of claim 8,wherein an external compensation period, in which a change in electricalcharacteristics of the driving TFT is sensed, is further assigned to thevertical blank period, and wherein the panel drive circuit applies thescan control signal and the sensing control signal through the sensingtarget pixel line to couple the gate node and the source node of thedriving TFT to corresponding signal lines during a sensing periodincluded in the external compensation period to prevent the gate nodeand the source node of the driving TFT from being electrically floated.12. The touch sensor integrated display device of claim 1, wherein thesensing target pixel line includes two or more pixel lines, the paneldrive circuit simultaneously drives sensing target pixels, that aredisposed vertically adjacent to one another and coupled to the two ormore pixel lines, and simultaneously samples sensing values of thesensing target pixels through the sensing line coupled to the sensingtarget pixels.
 13. The touch sensor integrated display device of claim1, wherein the sensing target pixel line includes two or more pixellines, the panel drive circuit sequentially drives sensing targetpixels, that are disposed vertically adjacent to one another and coupledto the two or more pixel lines, and simultaneously samples sensingvalues of the sensing target pixels through the sensing line coupled tothe sensing target pixels.
 14. The touch sensor integrated displaydevice of claim 1, wherein the timing controller includes: a memory; anda memory controller configured to store image data input in the memoryat a first frame frequency and output data stored in the memory at asecond frame frequency less than the first frame frequency.
 15. Thetouch sensor integrated display device of claim 1, wherein a touchcapacitor caused by the touch input is connected to the gate node or thesource node of the driving TFT and changes the gate-source voltage ofthe driving TFT.
 16. A method for driving a touch sensor integrateddisplay device, in which each pixel of a pixel array includes an organiclight emitting diode (OLED) and a driving thin film transistor (TFT)applying a source-drain current to the OLED, the method comprising: afirst step of setting a touch sensing period with respect to a displaypanel, in which the pixel array is divided into a plurality of touchblocks, each touch block including a plurality of pixels and a sensingtarget pixel line coupled to a subset of the plurality of pixels, thesensing line being coupled to another pixel in another touch block; asecond step of, in the touch sensing period, supplying a scan controlsignal and a sensing control signal to the sensing target pixel linecorresponding to a touch block of the touch blocks, setting agate-source voltage of the driving TFT coupled to the sensing targetpixel line to turn on the driving TFT by applying a touch driving datavoltage to a gate node of the driving TFT and applying a referencevoltage to a source node of the driving TFT, and outputting a sensingvalue by sensing, through a sensing line coupled to the driving TFT, achange in the source-drain current of the driving TFT caused by a touchinput, the sensing line coupled to one or more pixels in the touchblock; and a third step of comparing the sensing value with apredetermined reference value to detect the touch input based on thecomparison.